Marine steam-turbine.



Patented Nov. 14, 1911.

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MARINE STEAM TURBINE. APILIUATION IILED NOV.19,1910.

Patentud Nov. 14, 1911.

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cue. CURTIS. MARINE STEAM TURBINE.

APPLICATION FILED NOV. 19,1910.

Patel ted Nov. 14,- 1911.

6 SHEETS-*SHEET 3.

Witnesss Inventor Attomcyl.

G. G. CURTIS.

' MARINE STEAM TURBINE. APPLICATION FILED Novflla, 1910.

Patented Nov. 14, 1911! 6 SE BEETS-SHEET 4.

G. G. CURTIS.

MARINE STEAM TURBINE.

APPLICATION IIL'BD NOV. 19, 19101 Patented NOV. 14, 191 1 6 i BEETS-SHEET 5.

Inventor 4. 66.02:;

.0. G. CURTIS. MARINE STEAM TURBINE.

APPLICATION FILED N0V119, 1910.

Patented ov. 14, 1911.

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Specification of Letters Patent.

- Patent ed Nov. 14, 191-1.

Application filed November 19,1010. -8erial No. 593,161.

To all whom it may concert".v

Be it known that I, Cnnnms G. Guam, a citizen of the United States, residing at New York city, in the county and State of New York, have invented a certainnew and 'useful improvement in Marine Steam-'lurbines, of which the following is a specification.

The object I have ,111 View isto simplify and cheapo-n the construction and repair and also to increase the efficiency of marine steam turbines, particularly those having initial et impulse-stages.

My present invention is an improvement upon that setforth in my a plication for patent of even dateherewit (Serial No. 593,159), and consists in art in-a novel construction whereby the prlnciple of balancing the thrusts, including that of the propeller, by reversed drum pressure stages, set forth in that application, is made useful in a marine steamturbine having turbine elements of substantially equal power mounted on separate shaft-s. y

The invention is applicable to a 4-shaft arrangement where two turbines are em-.

ployed, each consisting of a high and a low pressure element of substantially equal )ower mounted on separate shafts and takmg the. full steam flow in succession. It is also applicable to a 3-shaft arrangement wherein a single'tu'rbine is employed consisting of three elements, a high pressure element mounted on one shaft and two low pressure elements mounted on the other two shafts and taking the steam in multiple from the high pressure element, all three of said elements being designed to develop substantially equal power. In carrying out this mof my mvention in the twof element t-ur ine consists of a number of initial 'jet wheel.

where the ower is equally divided btween the two s afts, I emlploy reversed drum stages in the low as we as in the high pressure element of the turbine, the steam pressure entering the low pressure element being'so high that it would be impracticable to em loy it on a. direct drum stage to neutra ize the thrust of the propeller. The

high re'ssure element also has one or more imtia jet wheelstages. In the three'element turbine, 'where each shaft does onethird the work, the high ressure element stages and a drum pressure stage having a small enough pressure difference to practically neutralize the ropeller thrust, and the two low pressure e ements, between which the steam is divided eiually, are rovided ;w1th reverseddrum pres ure stages,t esteem pressure at the admissi )n end of these 0310- ments being too high for direct use in 00 neutralizing the propell :r thrust.

Another feature of my invent-ion, which is applicable to my murine steam turbine having reversed drum 5 :ages whether made complete in one casing 31' divided into two or more elements, consists in using several initial jet wheel sta es mud in having stage valves for each of t est wheel stages so as to enable the adjustment of the pressure distribution under cruising conditions in such,

way as to get the most iiflicient result The drum stage following th a wheel stages has a definite steam passage area which there is no means of reducin and, by reason of this, when the steam he cruising conditions the 1 ressure at the head of this drum stage drips. very decidedly. For example, at full po ver the steam pressure at the head of the li rst drum stage may be 70 pounds, whereas wl en the steam flow is .80

reduced for cruising, thi: pressure may drop to 20, or even 10, pounds. .Under these conditions, unless the nozzle areas of the several preceding wheel stagesire reduced in cer tain p'i' oportions the .wh el stages after the first will do very littlt or practically no work. By regulating tie steam pressures by means of stage valves. to suit the reduced steam flow existing under one or more cruis' mg conditions, these velo nty stages after the first can be made to do a large amount of work, and thereby secul e an increased efliciency of the turbine.

In the drawing the t vo-element turbine isshown in Figures 1 to 11, while the threeelement t-urbineis shown in Figs. 12 and 13. Fig. 1 is a longitudin 01' section of the upper half of the high pressure element of the two-element turbine F' 2-is section (on the line.2 *2 in F: g. 3

for the first jet wheelsts ge; Fig. 3 is a section of the first stage sieam chest on line 3 -3 inFig. 2; Figs. 41.1 id 5 are sections on- Fig. 6 ism longitudinal section similar to Fig. 1 of the low press [1'8 element of the turbine, the section of the, steam passages 110.

being taken on line 6-45 in Figs. 8 and 9;

Fig. 7 is a longitudinal s4 ction taken .on line w is reduced under 75.

through the loo nozzles, steam chest and controlling valves elevation of the assembled turbines;

77 in Figs. 8 and 9; Figs. 8.and 9 are-cross sections taken on lines 8-8 and 9.9 -re-'- spectively in Fig. 6; Fig. 10 is a plan view of the engine'room of a 4=-sh'aft ship showing two of the turbines illustrated by the other figures. assembled; Fig. 11 is a fore I nd 1g. 12 is a half longitudinal section of thehigh ressure element of the three-element turine, showing in outline the head' of the casin of one of the low pressure elements; and ig. 13 is a plan, view illustrating the elements of the three-element turbine assembled ina 3 -shaft arran ement.

Referring first to the igh pressure element of the two-element turbine shown in Figs. 1 to 5, the shaft 12 carries the rotating parts while the stationary parts are carried by the casing havin sides 13 and fore and aft heads 14, 15, t rough stufiing boxes 16, 1?, in which the shaft passes. As

shown, three initial ljet wheel stages are employed whose whee s aretshown at 18, 19 and 20-and the twoseparating diaphragms are indicated by 21 and 22. The casm head 14 has one or more covered man-'ho es or hand-holes 23 for givin accessthrough one ormorcopenings in t e web of wheel 18 to the bushing or packing of the diaphragm 21 while one 'or more covered man'holes or hand holes 24 in the diaphragm 21 give access in a similar manner to the bushing or packing of the diaphragm 22. The first stage nozzles 25 are carried by the head 1 while the second and third stage nozzles 26, 27 are carried b Following the' third wheel stage is a drum pressure stage whose drum 28 is su ported from the'shaft in part by a steam tigllt head 29 which closes the steam space between the drum and the shaft and is formed and proportioned'to withstand the press'ure'difierenceto which it will be subjected without change of shape. The first dru'm stage includes a number of annular rows of moving and stationary buckets operating on the impulse or reaction rinciple and having a completeperiphera admission of the steam. The first drum' stage receives the steafn di: rectly from the last wheel stage and delivers it to aspaoe 30 in front of a diaphragm 31, where it. enters pipes 32 leading to a chamber 33 inside the aft head 15 from which it enters a second drum pressurestage similar to the first drum stage, but reversed with respect to the steam flow. The drum 34 of the second drum stage has a pressure head 35 similar to the pressure head 29, butadaptedto resist a ressure difference exerted in the opposite direction. The steam from the second drumstage is discharged into a space 36 aft of the diaphragm 31 from whichone or more pipes 37 carry the steam to'the low pressure element of the turbine. The steam pressure drops. in passing through' each the diaphragms 21', 22.

nooaasi on the heads 29 and 35 and exerting thrusts in opposite directions on the shaft. By proportionin the steam passa' e areas through the rum stages to secure t e proper pressure drop between the two ends of each drum stage and by having the thrust areas at the drum stages of the pruperrelativ in my ap lication referred to, a partial balancing o the thrusts within the high pressure element of the turbine, leaving a resulta nt turbine thrust opposed to and wholly powers the. thrust of the propeller which is ing conditions, stage valves are employed, as already stated. The disk valve 38, 39 Figs. 1 and 2) close respectively fifteen an sevr enty per cent. of the first stage nozzles, the remalning first stage nozzles equal to 15 per cent. of thefull steain flow being left constantly open. Corresponding portions of the nozzles of the-second and third stages are also left open. The slide valves 40, 41 at the efiicient pressure distribution when the steam flow is reduced by closing the correspondin first stage valves. For example, at full loa all the stage valves being open, the steam in pounds absolute, 100, and 72, the'last pressure being that at the head of the first drum stage; at 30% steam flow, produced by closing the large valves 39, 41 and 4:23, the corres onding steam pressures may be 100, 46 an 21 pounds (gabsolute); and steam flow, produce by closing all the stage may be 100, 35 and 11 pounds (absolute). This result will be'secured by -proportionin stage valves substantially as shown in the drawing. Any desired different distribution of pressures can be secured by properl proportioning. these valve-contro lednozz o -areas., If by maintaining the first sta e pressure the same at lower powers as at fu power, thrust, produced, by this pressure on the shaft-thrust area resultin from stepping down the shaft at its eni, should, in the particular design of the turbine, be larger than desired at less than ffnllpower, the stage valves could be proportioned to drop the pressure in the first stage to any desired extent,

The low pressure element of the turbine (Figs. 6, 7, 8 and?) is mounted on a shaft 44 which carries .the rotating parts, while the stationary parts are carried by the easing whose sides are indicated by 45 and its fore head'by 6. The shaft--passcs through amounts, there will be secured, as explained mounted upon the same shaft. For securing. increased economy under one or more cruisthe areas covered by the second and'thir drum stage producing a pressure difl'erenc6 or largely neutralizing at all substantial second stage nozzles and the slide valves 42, 43 at the third stage nozzles secure an pressures in the three wheel stages may be,

valves, the corresponding steam pressures the thrust, opposed to. thepropeller stuiiing'boxes in the heads of.the casing,,the.

and the steam passes-through this stage in a forward direction so'that the ressure difference on the head 4-9 exerts a tirlist inthesame direction as the propeller thrust. The pipes 37 from the high pressure element connect with a'chamber 50 m the fore head 46 from which channels 51 in the sides of the casing lead aft to a chamber 52 at. the admission end of drum 48, which chamber 52 is closed on its aftside by a diaphragm 53. The steam flows from the chamber 52 forward through-the first drum stage of the low pressure eltiient and discharges into an annular space :S-t-at the fore head 46, from which it 1s= carried aft through channels 55 inthe casing to the aft side of the diaphragm 53. Here it enters a second drum pressure-stage similar to the first drum stage, but carrying the steam aft-ward instead of forward; Its drum 56 has a steam tight Lpressure head 57, the diiiercnee in pressure upon which exerts a thrust on the.

shaft opposed to the ropeller thrust. -'.lhe second drum stage of the low pressure element discharges the steaminto the exhaust 58,1the pressure head 57 being exposed to the exhaust pressure on its aft side. The chamber 52- which affords room for the rewin and replacement, in segments, of the bushing or packing of the diaphragm 5? is accessible through covered man-holes or hand-holes 59, (30. 'The reversing element (31 o, the turbine is also inclosed by the easing of the low pressure element. It is shown in part at the left in Fig. 6.

In order to give the low pressure element substantially the same power as the high pressure element the pressure of the steam enterin the low pressure element will be too higrtfor example, 19.25 pounds, absolate, at full power) for use in neutralizing the propelleutlnust by a'singlc drum stage with thelargepitch diameter necessary to isfactory length of the turbine. Hence I employ the reversed drum stige. By proportioning the steam passage areas through the two drum stages'to s ecure the proper pressure drop between the two bnds of each drum stage and by having th} lhrustarea's at the drum stages of the proper relative amounts, there will'be secured,'as explained in my application rrferred tyne partial neutralization of the thrusts within the low pressure element of the turbine, laring -a j resultant. turbine "thrust opposed to and 'wholly. or lai'gely'neutralizlng at all substantial powers the thrust. ollthe 5 which is-mounted upon the salne's aft.

ivethe desired low shaft speed with" a satropeller p In Figs. 10 and 11 tv 0 of the two-element turbines are shown as ambled in a t-shaft arrangement. A and B are the high and low pressure elements of each turbine, the ,latter including the rtversing elements 61. The high pressure elen ents are mounted on thc'wing propeller sha its 12, while the low pressure'e ements are n ounted on the center propeller shafts 44. The thrust blocks of the several shafts which take the unbalanced thrust, if any, 0 18: way or the other, are indicated at 62.

The three-element tl'rbine '(Figs. 1:"! and 13) comprises a high pressure clement C and two low pressure elements I) and E, of substantially equal power, mountedon the centerand wing propeller shafts-'63, (it and 65, having thrust block; 62. The high pressure clement C has three initial jet wheel stages whose wheels at! shown at (56, (37 and 68,-and whose -separating diaphragms are shown at 69, 70. The: e are followed by a short drum pressure sage whose drum 71 is supported from the s iaft by a steam tight .pressure head 72. Thi drum stage carries the steam in the same direction as the preceding wheel stages a 1 d produces a thrust opposed to the propelle thrust. The power being divided equally between the three elements of 'the turbine and a higher steam pressu're (forexample, 40 pounds, absolute, at full power) being rtquired at the admissicn end of the low pressure elements I), E. to'develop the same power with one-half the stea1n flow, than with the low pressure 199 clement B of the two-e ement turbine which receives the full stean how, it is possible to secure the necessary reduction in steam pressure in the hi'ghp 'essure element C in advance of the drum st: ge by a limited num- 195 ber of wheel stages. onsequently the. propeller thrust on the st aft 63 on which the element C is lIlUlllliOt can be practically neutralized at all subrtantlal powers by a single direct drum st age in this element E, has, like the element B, reversed drum 120,

pressure stages which )artially balance the thrusts within the clean ent, leaving a resul ant thrust opposed to' and practically neutralizing at all substani ial powers the thrust of the propeller. The 1 tin pressure elements D, E, also have, iikc the element B, each a reversin turbinei elei ient within the same. casing. The high press are element C is also i-eferably provided w nth stagewa'lves ha,ving thc same function as the stage valves 3 of the high pressure element A; A ditferent construction of the'valves for the second and third sta 'es is shown in connection with the element 3, which may be used in place of the slide valves of element A. Steam chests 75, 7 6' for the second and third wheel stages are secured on the outside of the turbine casing, and the second and third stage nozzles are carried by the casing. The first and second stage buckets discharge into chambers 77, 78 opening outwardly through the easing into the steam chests 75, 76, and disk valves 79, 80 control the. flow of steam from the steam chests 75, 76 to the nozzles of the second and third stages. It will be understood that, as in the case of the first sta-e nozzles of the high pressure element A, the passage from the steam chests 7 5, 76 to the nozzles will be divided into three sections of the desired nozzle area and that there will be separate valves for each stage for controlling two of these. sections so as to secure, with the disk valves, the same character of control of the steam flow in the second and third wheel stages of element C as with the slide valves for the second and third wheel stages of element A. i

What I claim is 1. In a. marine steam turbine, the combination of high and low pressure elements mounted on separate pressure element producing a thrustopposed to the propeller thrust on the high pressure. shaft, and reversed drum pressure stages in the low pressure element producing thrusts opposed to the propeller thrust on the low pressure shaft, substantially as set forth.

2-. In a marine steam turbine, the eombi nation or high and low pressure elements shafts, means in the high shaft, substantially as set forth.

mounted on separate shafts and reversed drum stages in each element, reducing thrusts o' posed to the thrust of t e propellers on he two shafts, substantially as set forth.

3. In a marine steam turbine, the combination of high and low pressureelements mounted on separate shafts, one or-more initial jet wheel stages in the high pressure element, means in thehigh pressure, element producing a thrust opposed to the propeller thrust on the high pressure shaft, and reversed drum pressure'stages in the-low pressure element producing a thrust opposed to the propeller thrust on the lowpressure 4. In a marine steam turbine, the' .combination of high and low pressure" elements mounted on separate shafts, one or more initial jet wheel stages in the high pressure element and reversed drum stages in each element producing thrusts o posed to the thrustof the propellers, on tlie two shafts, substantially as set forth; 4 v

5. In a marine steam turbine, the combination with reversed drum stages, of-two or more initial.jet wheel stages and stage valves controlling the areas of the nozzles of the several wheel stages so as to increase the etlieiency of the'turbine under one or more cruising conditions, substantially as set forth.

This specification signed and witnessed this 15th day of November, 1910.

CHARLES, G. CURTIS,

\Vitnesses:

J mm L. Lo'rscn, GUSTAV Scnsnmcn. 

